Correction to: Nature Structural & Molecular Biology https://doi.org/10.1038/s41594-020-0417-5, published online 25 May 2020.

In the version of this article initially published online, the grant number for the National Institutes of Health grant awarded to N.C. and G.W.A. was incorrect. The correct grant number is R01DK041544. The error has been corrected in the print, PDF and HTML versions of the article.